Spark-plug.



F. CARLSON.

SPARK PLUG.

APPLICATION FILED FEB. I. 191e.

5l/Witwen@ FREIDRICK CARLSON, OlE NORTH EASTON, MASSACHUSETTS.

SPARK-PLUG.

recente.

Specification of Letters Patent.

Patented lDec. 12, 1916.

l lAppli-cation` led February '7, 1916. Serial No. 76,659.

.North Easton, in the county of Bristol and State of Massachusetts, haveinvented cer-- tain new and useful Improvements in Spark Plugs; and I dodeclare the following to be a full, clear, and exact description of they invention, such as will enable others skilled in the art to which itappertains to make and use thesame.

This invention relates to new and useful improvements in spark plugs,and the primary object of the invention is to provide a spark plug thatwill be foundvery efficient in operation, and also which is pro videdwith an electrode that is self cleaning and will not become in any waychoked during the operation of the plug.

A further object of the invention isto provide a device of thischaracter which is simple and durable in construction, inexpensive tomanufacture, and one which will be very efficient in operation. l

With these and numerous other objects in view, myinvention consists ofthe novel features of construction, combination and arrangementof partswhich will herein be referred to and more particularly pointed out inthe specification and claim.

lin the accompanying drawing: Figure 1 is a central vertical section ofmy improved spark lug; Fig. 2 is a centraly vertical section of) theplug showing the electrode and core in elevation; Fig. 3 is adetailelevation of the core and electrode removed from the plug; andFig. 4 is a bottom plan view of the plug.

lln the general construction of my spark plug, the main parts aresimilar to those commonly used in' devices of this character, and theycomprise an outer shellor casing 1 which has its lower end 2 externallythreaded as shown at 3, so that the same may be screwed into the enginecylinder. Within the lower end 2 o f the casing 1 is formeda gas chamberA, for a purpose to be hereinafter more fully described. A suitableinsulating core 4 preferably made of porcelain, and having an annularenlargement 5 intermediate its ends, is adapted to be positioned in thecasing1, the enlargement of the same being positioned on an internalshoulder 6 in said casing. 'llhe core 4 is held in place by a retainingnut `7 as I clearly shown in Fig. 1 of the drawing. `The centralinsulating core 4 has its upper end projecting from the casing 1 as iscommon in devices of this character, while the lower end 8 of the sameis contracted, and is ter minated av predetermined distance above thelower edge of the casing in the gas chamber A. l

The insulating core 4 is provided with a central longitudinallyextending electrode 'rod 9 which extends therethrough and projects fromthe same at either end. A metallic cap 10 and binding nut 11 are screwedonto the upper end of the rod for the usual purposes, while the lowerprojecting end of said rod which is designated by the numeral 12vextends from the core within the chamber A to a point adjacent thelower end of the same. Surrounding the rod 12 at the lower end of thecore 4 is a steel washer 13 which will protect the terminal of the lowerend 8 of the core. Positioned on the projecting lower end 12 of the rod9 is a steel, substantially frusto-conical shaped electrode 14, whichhas its upper flat top positioned' against the bottom of the washer 13,while the sloping wall 15 of the same projects downwardly until itterminates at the outer edge 16 of the base 17, which is disposedadjacent the lower end of the casing. The base 17 is rounded and has itsannular outer edge 16 when in position, spaced equi-distant from thelower end of thev casing 1. The upper flat top of the electrode is of adiameter equal vto the diameterof the washer 13 and when positionedagainst the lower surface of the Same, its outer edge will be disposedin alinement with the vouter edge of said washer. This washer 13, owingto the fact that it is of a size corresponding to the lower extremity ofthe core 4 against which 1t is positioned, has its outer edge aliningwith the circumference of the lower end of the core, so that whenassembled, these parts will be all positioned in a single arc as clearlyshown in Figs. 1, 2 and 3 of the drawing. l

When the parts of this plug are assembled and the frusto-conical shapedelectrode is positioned against the Lower end of the core 4 -within thegas chamber A, `it will be noticed that the extreme outer edge 16 of thesame will be positioned a short distance from the lower edgey of thecasing, thereby forming'a circular communicating passage between thechamber A and the cylinder which is designated by the letter X.

When this device is in operation, the spark will jump from the edge 16of the electrode to the adjacent portion of the lower edge of'the-casing, and a large circular spark will be created by this gapwhich will be ample for any purpose to which this plug may be used. Assoon as the spark ignites the charge in the cylinder, an explosion willtake place in the gas chamber A, and the discharge of the expanded gasesthrough the communieating passage that is formed by the spark gap at'X,will prevent any accumulation of carbon deposits on the wall-of theelectrode by preventing the adhesion of lubricating oil and subsequentcarbon deposited thereon due to the burning of such oils. kThisoperation will make my improved spark plug selfcleaning and'will alsoprevent the same becoming choked up and stopped during its operation. This operation forms one of the most essential features of thisinvention, and

lthe same is brought about by the peculiar construction of theelectrode, that is so connected with the lower contracted end of thecore that an arc is formed thereby which upon explosion in the gaschamber will direct all of the gases downwardly with full force againstthe sloping wall of the electrode. This brings about the self-cleaningaction that will always keep the point adin its lower end, said chamberhaving an opening in its upper end larger than the open lower end of thesame, a continuous uninterrupted downwardly beveled edge at said lowerend of the chamber, an insulating core in the casing with its lower endextending downwardly in the gas chamber through the open upper end toform an annular chamber therein, said lower end of the core beingarcuately contracted and terminating a short distance from the loweredge of said chamber, a centrally disposed electrode rod in the coreextending from the lower end thereof, a washer on the lower end of saidrod, a substantially frusto-conical shaped electrode in the lower end ofsaid rod having a flat top engaging said washer and its lower edgespaced equi-distant from the upper portion of the outwardly beveledlower edge of the gas-chamber to form a spark gap therebetween, the wallof said electrode being arcuately curved and merging at its upper edgeinto the arcuately contracted lower end of the core to increase the areaof the annular gas chamber at that point, and the lower power ofthe wallof said electrode being inclined outwardly at substantially the sameinclination as the beveled edge of the gas chamber, whereby upon eX-plosion of the gases in the chamber they will be directed downwardlywith `flull force against the wall of the electrode and hence outthrough the spark gap which will keep the said gap free from carbon.

In testimony whereof I have hereunto set my hand in presence of twosubscribing witnesses.

Y FREDRICK CARLSON( Witnesses: l

ARTHUR G. CARLSON, FRANK I. KEITH.

